1. Field of the Invention
Aspects of the present invention relate to a rechargeable lithium battery. More particularly, aspects of the present invention relates to a rechargeable lithium battery having an excellent cycle life.
2. Description of the Related Art
Because lithium secondary batteries that include a non-aqueous electrolyte are known to generate a high voltage, and have high energy density and good storage characteristics as well as good operability at a low temperature, lithium secondary batteries are widely used in portable personal electronic devices. Accordingly, development has continued for high-capacity batteries as an electricity source of electronic devices.
In order to provide high-capacity batteries, metal materials such as Si, Sn, and Al have been developed as novel materials to be substituted for carbon-based negative active material. However, a rechargeable lithium battery including a non-carbon-based negative electrode typically has an improved capacity compared to a lithium battery including a carbon-based negative electrode, but typically exhibits a poor cycle life. For example, high-capacity batteries using these metal materials as a negative active material have not yet been commercialized because the metals such as Si, Sn, Al, and so on tend to form an alloy with lithium during charge-discharge cycles and undergo volume expansion and shrinkage resulting in pulverization. As a result, the cycle life of batteries may deteriorate.
Therefore, amorphous alloys have been suggested as a negative active material to improve cycle-life characteristics. Amorphous Si oxide alloy materials have relatively higher initial capacity retention than crystalline alloy materials, but the capacity retention thereof may be sharply decreased after repeating charge and discharge cycles.
Moreover, Korean Patent Laid-Open Publication No. 2006-41828 discloses that an electrolyte including a halogen-containing carbonate such as 4-fluoroethylene carbonate improves cycle-life characteristics of a battery including the non-carbon-based negative electrode, but the improvement is limited.